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First time accepted submitter JoshuaZ writes "Astronomers have found an unusual small star. SDSS J102915+172927 is a small faint star with very little of any elements other than hydrogen or helium. The star's composition is surprising (Pdf) since standard theories of star formation require heavier elements in small stars in order to allow the stars to be heavy enough to come together. Possibly the most unusual aspect of this star is the complete non-detection of lithium which would be expected in a star of this size. The only elements created shortly after the Big Bang were lithium, hydrogen and helium, and the star should have lithium levels much higher since they should correspond closely with the levels believed to have been formed shortly after the Big Bang."

I've always found Occam's Razor an interesting thing to invoke in cases like this. While I agree with the contention that the simplest explanation is likely the right one, that statement means nothing at all if you don't have a pretty good sense of the situation.

The assumption that its considerably more likely our theories of star formation are wrong is based on a couple presumptions that may be correct, but may not:

- life is uncommon- intelligent life is even more uncommon- intelligent life goes extinct be

While I agree with the contention that the simplest explanation is likely the right one

Why would you agree with something so nonsensical? And why would you state such a belief in the context of Occam's Razor, which says nothing of the kind. Occam's Razor says that, if a model works without one of its factors, then it is safe to remove that factor. It's a rule about logic, not about science. If you start with a set of axioms and develop a system, then there are an infinite number of axioms that you can add without changing the validity of any of your interred rules, but adding these does not gain you anything.

An example of its application in science is the idea of guided evolution. One model suggests that species change via random mutations. Another model suggests that these changes are not random, that they're guided by a higher power in such a way that is indistinguishable from random change. Occam does not say that the second hypothesis is wrong, merely that it adds nothing useful to the model. You could also add another factor to that saying that it's guided by a higher power who makes decisions based on what an angel tells him. You could go on adding extra layers to this hypothesis forever, without altering the predictions that are made. You can, therefore, save yourself some mental effort by ignoring the factors that are irrelevant.

That doesn't mean that the first theory is 'right', or true, it just means that it's simpler and equally useful.

None of those assumptions remotely approximate the least degree of scientific consensus - the debate is still strongly happening on them.

The evidence we do have can support two conclusions:1) Life is very fragile and that it happened on earth at all is rare, unique and may never have managed to happen anywhere else.2) Life is very resilient and has survived despite everything the universe has thrown at is (mostly giant, icy rocks) and continues to survive everywhere it can and everywhere it can't.

"fragile" really isn't the right word for your first statement. The question is what are the chances of a bunch of molecules coming together in just the right way for life to happen (ignoring panspermia or divine intervention, both of which I consider equally (un)plausible). This is hard to answer, so life could be everywhere or nowhere but earth. Once it occurs it rapidly diversifies which makes it very robust.

No, it's based on how difficult it would be to mine elements from a star. We *know* that is difficult to the point of near-impossibility; we *guess* that the universe started with a big bang (and we are trying hard to make a theory with a lot of holes fit better, since it fits the best of the various pretty bad theories we have.)

The OP said the star was mined. I responded by questioning our star formation theories instead because it's a much simpler and more likely place to find an answer. As opposed to ali

>It's considerably more likely that our theory(/ies) of star formation are lacking.

It's even MORE likely that our theories are generally correct but some specific unknown circumstance caused this particular star to follow a different and unexpected path. This star is not matching the previously observed observations on which our theories are based. The most likely explanation is that something highly unusual (perhaps entirely unique) happened here - we don't yet know what, something that cause it not to

It does vary a little bit from location to location due to altitude, physical geography, presence of mountains (or lack thereof), and other factors, but in general you are correct with that measurement.

BTW, that makes for a great high school physics assignment to calculate within 2-3 decimal points the local gravitational acceleration rate. Using a sports timer or photo-optical timing device, or even simple stop watch and dropping something off a roof can give you some pretty accurate values for calculatio

1) People calling something "dark" doesn't mean they literally believe that, for instance, "dark energy" exists. What they know is that observations cannot be accounted for without something that acts the way "dark energy" acts, in the equations they currently employ. There is enormous research in this field pursuing a wide range of approaches to reproducing the observations theoretically. The simplest models employ a "dark energy" -- literally, something that does not interact with light, and which has a pressure sufficiently negative as to accelerate the expansion of the universe. No-one -- and I mean NO-ONE -- who works in the field treats these as anything other than toy models. Phenomenology, to use the jargon. More complex models attempt to see what changes to the assumed laws of gravity are necessary to reproduce the effect. No-one who does this pretends that their model is anything other than a toy model. (Indeed, most modifications to gravity can be rephrased as a dark energy of the first kind anyway, albeit a really weird, ugly one. It's the motivation that's different.) More controversial models attempt to reproduce the observations by changing one of the fundamental assumptions that lead to the standard cosmological model: homogeneity. Violate homogeneity and you can influence the paths of photons around us in ways that mimic "dark energy". No-one working on this pretends that it's anything other than a toy model. Yet another approach is to point out that the universe is intrinsically inhomogeneous and anisotropic and attempt to reconstruct the homogeneous universe we employ in cosmology from that. No-one working on this pretends that the models studied so far are anything other than toy models.

It's not "scientists" "making up" "dark" "somethings" that can be "plugged into equations" but "never detected", it's people tagging a puzzling observation with a placeholder ("dark energy" for the anomalous acceleration of the universe; "dark matter" for the apparent necessity across a massive range of scales for large amounts of clustering matter that doesn't interact with light) and then exploring potential explanations.

I don't care if you were trying to joke. This kind of accusation really annoys me because it suggests that either we're terrible at explaining what's going on, or people simply aren't listening to us;, or both and people who argue this way tend to insinuate that those of us in astrophysics are a pack of idiots or charlatans fraudulently inventing arbitrary and unobservable physics in order to screw millions upon millions of euro from the honest taxpayer. And that's frankly offensive.

Fine. Send me a copy of your proposal and I'll see what we can do with it. You'll get first author status on the first paper, which will be to take your non-incompetent alternative and extract from it the CMB -- its monopole and its higher multipoles. If it can also explain the dipole then that's even better. The fit has to be significantly better (quantifiably significant; that means I have to be able to find the Bayesian evidence and find it to be significantly better on a well-defined scale, rather than

Considering that Helium (derived from the Greek name for the Sun, Helios) was first detected on the Sun and other stars well before it was found on the Earth, I would say that the ability to detect elements from an incandescent body to be rather good. We certainly know more about the minerals inside distant stars better than we do rocks underneath us more than a mile or two deep.

The detection of elements in stars is as close to an exact science as you can get, where the mathematical relationship for how th

Mine the Giant Molecular Clouds where stars are made. If you wanted to make lots of Dyson sphere habitats, O'Neil Cylinders, or Jupiter Brains, that is where you would do it. The resulting stars would lack whatever elements you really needed.

The real question is, why would they want all of the lithium ? Maybe for fusion power (as Castle Bravo showed, lithium-7 captures a neutron and splits into an alpha particle, a tritium nucleus, and the captured neutron, and tritium / Helium fuse well). Either such minin

So rather than dealing with the star directly, lets say it was possible to push.pull all the planets further and further away... how would that affect the rotational velocity? (assuming a Sol-like solar system)

Reduce the circumference, and rotational velocity increases proportionally. If enertial mass is uneffected, the heavier elements would spin out to the sides, leave the artificial gravity well, and fly off?

Reduce the circumference, and rotational velocity increases proportionally. If enertial[sic] mass is uneffected, the heavier elements would spin out to the sides, leave the artificial gravity well, and fly off?

I'd be careful with a technology that powerful, you might end up creating a black hole:p

Perhaps it would be easier to just transmute other elements into the ones we need?

At the end, it's a question of energy. Stars are big. If you're accustomed to the scale of a planet, they're really big. You could transmute all of the hydrogen in Jupiter into more useful elements, but the energy required would be huge. The sort of energy that you'd get from... a star. And if you're going to the effort of tapping a star's energy at that level, then you may as well skim off the elements too. Additionally, if you're capable of inducing gravity, then a star is a pretty good place to per

On a more serious note: given that the Milky Way's diameter is ~100,000 light years, this thing being only "3,500 light-years above the disc of the Milky Way" would make it a straggling member of our galaxy, would it not?

I always like to know how far away something is from us. Most articles on the web give direction toward Leo, but for distance I only found one reference that said it was hovering 3,500 light-years above the disk of the Milky Way. So it's near our Milky Way

That's because it is so damn hard to measure distance, so sometimes even an approximate distance is not given (but as you imply, distances should be given when known or a reasonable guess is available). That's because the most straightforward way requires you to know the 'extinction' of light towards your particular star. That means, you need to have a measurement of blocking effect of (non-emitting) gas nearby and hope it applies to your (hopefully nearby) object of interest. If you are lucky you'll get a reasonable estimate for distance that is probably within an order of magnitude of the true value, and sometimes you might even get down to a factor of two in uncertainty. And this is just for stuff relatively close in our galaxy. Getting distances elsewhere can be even harder. Disclaimer: IAAFA (I am a former astrophysicist).

For a main sequence star, the procedure would normally go something like this:From the star's spectrum, you know its temperature. (With a good enough spectrum, you can also confirm that it is main sequence.) From the temperature and the fact it is main sequence you know its intrinsic luminosity pretty well. From its temperature you know its intrinsic colour well. Comparing this to the observed colour, you infer how much dust there is between you and the star. (Dust blocks blue light more strongly than red light, so more dust means redder colour.) Knowing how much dust there is, you know how much its observed brightness has been reduced by the dust. Knowing what its brightness would be without dust and its intrinsic luminosity, you use the inverse square law to figure out how far away it is.

However, this star would have a really weird spectrum. If I recall correctly, hydrogen and helium only show spectral lines in much hotter stars, so presumably the only lines are calcium (the only metal they did detect). I don't know how well they can determine temperature with just calcium lines. I'm also not sure how precise this procedure is on ordinary stars, but I'd guess the uncertainty in distance would be about 10-30%.

IAAFA also, but I've never actually used the procedure I describe above.

No, seriously, thanks for the explanation. Regarding the H and He lines - as a (bio)chemist, who admittedly hasn't done much optical spectroscopy lately, I still think that you should at least see the absorption lines regardless of temperature. Not sure how that would figure into temperature determination, but hey, I used to work with single molecules. Stars are way to big for me;)

The issue that comes from stellar spectra is that you have different layers emitting/absorbing light, so you get different characteristics depending on the temperature of the star and the temperature of its surface. So you get both absorption and emission lines, sometimes of the same element and certainly a healthy mixture of a great many elements simultaneously.

A whole lot of information is packed into stellar spectra together with the ability to "repeat" the measurement literally billions of times for ot

Sorry for replying again, but Slashdot doesn't allow one to edit comments.

Another relevant factor is that in red shift the spectral lines are shifted towards the red end of the spectrum. The reddening from dust does not shift the lines, just makes the blue part of the spectrum fainter.

yes, great stuff. but in this particular case they seem to know a rough approximation of distance but instead only gave us equivalent of projection onto one coordinate axis. So let's see, galactic center is about 19 hour RA and -25 degrees down. Leo (and so roughly this star), is 11 hours RA and +15 degrees up. the main thing being that this is roughly 40 degrees up from galactic center which we'll call the plane of the galaxy. So we make a leg 3,500 light-years up to the star from the plane if that

In a sense this is a good thing. It shows that when you really get down to it, we still really understand very little about the universe and how things are formed/created. A little humility never hurt.

The mass fraction of elements heavier than helium in this star is less than 1ppm. The sun is 99.9% H and He and only 0.1% heavier stuff, this star has some 50.000 times less than that. Compared to this star, Jupiter is solid iron, so no, not like Jupiter at all.

It is probably safer to say that they did not detect lithium in the star's atmosphere.

The light that we see from a star tends to fit a blackbody curve, which says a lot about the temperature of a star but nothing about the composition. However, the stellar atmosphere will contain absorption or emission lines that tell us about the composition of the atmosphere. It doesn't say anything about the interior of the star.

Now my recollections of stellar models is quite hazy, but I do recall that different proces

Why? The quantities of heavy atoms made in the original big bang nucleosynthesis are widely accepted to have been miniscule. Non-trivial quantities of elements heavier than beryllium didn't exist until stellar nucleosynthesis started. And beryllium itself was produced in such hilariously tiny amounts that it's usually forgotten.

By mass, the amounts of lithium and beryllium created during BBNS should be around the same order of magnitude. That may be very small, but nevertheless, the quote in the OP indicates that ONLY lithium hydrogen and helium were created. If your argument is that the amount of beryllium was so small that you can just pretend it's zero and use absolute language, then "no" lithium was created, either.

Yes ok. You are correct. I didn't mention beryllium. I'm not an astronomer or an astrophysicist but my impression is that the beryllium created was primarily in unstable isotopes like Beryllium-7 which have such a short half-lives that it would all decay before star formation even got started. Is that correct? If so, then this really doesn't matter for star formation issues. Although yes for technical accuracy I it probably would have been better to say something like "the only stable elements" or something

Wow, what is so unusual, you think you know what a star is made up of, especially when you can just take a sample and test it right there and then,not we have been hypothesizing at all here....

If we really knew what a star was made up of, then I would agree, however, the fact is we still have yet to be able to take real samples, and even so,we should not think that all stars are the same, or even that we have come across all possible star types.....

I'm not an anstronomer either, but the article summary did specifically say small star. The wikipedia article on red dwarfs mentions that as of 2009 there is a 'mystery' as to the absence of red dwarfs with no metals, and the preferred explanation is that without metals only large stars can form. So that theory allows for the bigger stars forming, creating heavier elements, and then exploding, spewing those elements out into the universe. Even if red dwarfs had been created at the beginning, they are

If god wanted to test our faith with impossible stuff, he could have simply made a huge mountain-sized boulder magically float in air over the vatican, defying gravity. Miracles are more appreciated when they are closer home.

The AC had an important point, though. What would they accept as "proof" of the existence of God? If they want scientific proof (as usually understood) of the Judeo-Christian God (as usually understood) then it's likely that it couldn't possibly exist. Any finite explanation of any set of observations would be simpler than an infinite God, and so would be preferred due to Ockham's razor. Some statements of the scientific method explicitly state that any explanation involving God or gods is to be rejected. S

As a fifty year atheist, I can tell you that it would take a discussion with God to convince me.

Anything else is just a matter of how someone figured out how to manipulate energy.

And if anyone wants to put forth the old 'sufficiently advanced aliens' stuff, any friggin' alien that can convince me face to face that it meets the requirements that I logically understand to constitute the minimum basis for God with a capital G makes that argument purely academic and I'll tell God you said so.

As a fifty year atheist, I can tell you that it would take a discussion with God to convince me.

forty-year atheist here (I was raised Catholic, but it didn't take).

Actually, even a "discussion with God" wouldn't convince me (since a more reasonable explanation is that I was hallucinating).

I don't want to spoil it for those who haven't read it yet, but "Contact" by Carl Sagan has plot that covers this in a (IMHO) brilliant way. Again, the movie minimized this particular plot line, and it ignored the d

Actually, some of us are pretty easy about it. Although the Christian God is contradictory enough to be impossible to fully demonstrate, I for one would settle for a much less powerful being as God. Or as a god.

And it's not just me. For 99% of the existence of the human species, we lived just fine with much less omnipotent gods. Even the Jewish God of the OT, actually promised a lot less. Heck, until very late, he didn't even promise an afterlife at all. (In fact, Genesis even spells it out that God _didn't

", He/She would be unable to prove His/Her existence to such atheists"

Allmight....unable...You don't see the problem with your own claim ?

If a God really wanted to prove his existence to such atheists he would have no problem, about half of Genesis is full of him manipulating the thoughts and feelings of Pharao to make him act stupidly just to prove a point !Clearly changing somebody's mind and notably their reaction to observations is something he already claims to have done.

", He/She would be unable to prove His/Her existence to such atheists"

Allmight....unable...
You don't see the problem with your own claim ?

No, no problem. Theologians decided many centuries ago that prefixing a meaningless statement with "Can God...?" doesn't make a meaningful question.

If a God really wanted to prove his existence to such atheists he would have no problem, about half of Genesis is full of him manipulating the thoughts and feelings of Pharao to make him act stupidly just to prove a point !

I wouldn't consider manipulating thoughts to be a proof. Rather, it gets around the need for proof, and they would no longer be "such atheists".

It says outright that faith must be based on nothing to be faith at all.

[citation needed]

This is what makes religious explanations by default unscientific. Religion by default rejects belief based on evidence

No, religion by default accepts belief based on evidence (Psalm 34:8). It just has accepts as evidence more than science does, and the additional things that they accept as evidence in very rare cases le

>No, religion by default accepts belief based on evidence (Psalm 34:8). It just has accepts as evidence more than science does, and the additional things that they accept as evidence in very rare cases leads them to different conclusions.

Now you're arguing semantics (stupidly). If I replace "evidence" with "empirical evidence" then you're entire argu

>No, religion by default accepts belief based on evidence (Psalm 34:8). It just has accepts as evidence more than science does, and the additional things that they accept as evidence in very rare cases leads them to different conclusions.

It doesn't fall flat. You say that religion rejects evidence. It doesn't. It doesn't reject empirical evidence either. It fully accepts empirical evidence and modifies its beliefs based on empirical evidence.

This is an absolute. The people who believe in god, believe he is almighty, ergo if he so chooses he could so do.

No. That's a fundamental misunderstanding of omnipotence that was dealt with in the early days of Christianity. As I have already explained, putting "God can" in front of a meaningless statement doesn't make it meaningful, and "Proof of God in a system that excludes pr